On the Supposed Isoindole Synthesis from o-Tolunitrile

Abstract

A recent communication¹ in this journal reported the reaction of o-tolunitrile with sodium in tetrahydrofuran to yield a compound, m.p. 123.5–124°, to which was assigned the isoindole structure 1. A plausible mechanism can be written for the formation of 1 involving reductive dimerization of the cyano groups of two molecules of the nitrile, subsequent 1,5-hydrogen shift from a methyl group, disrotatory electrocyclic isoindole ring closure, and finally air oxidation and tautomerization to 1. Nevertheless, the evidence presented did not require an isoindole structure. Moreover, it would be unusual for a primary enamine to survive.